patch 8.1.0681: text properties as not adjusted for deleted text

Problem:    Text properties as not adjusted for deleted text.
Solution:   Adjust text properties when backspacing to delete text.
diff --git a/src/misc1.c b/src/misc1.c
index 692d5c7..c2d2d19 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -2749,7 +2749,7 @@
 #endif
 
     // mark the buffer as changed and prepare for displaying
-    changed_bytes(lnum, curwin->w_cursor.col);
+    inserted_bytes(lnum, curwin->w_cursor.col, -count);
 
     return OK;
 }